Rapid Manufacturing Platform

"The backbone of the platform is the manipulation of trajectories in space" Jean-Yves Hascoët, Centrale Nantes professor, head of the Rapid Manufacturing Platform and pilot of the Additive Manufacturing component of the Joint Laboratory of Marine Technology.

The students of the Mechanical Engineering Master and the Product Engineering option have access to the platform during their laboratory work. Their practical classes are based on simplified industrial projects.

ADDITIVE MANUFACTURING ROBOTIC CELL

The cell accommodates a high-capacity robot, which allows a weight of 500 kg to be displaced 3 meters at arm’s length. This exceptional machine allows the hybrid manufacture of large parts. Hybrid, because it combines several processes: wire-based (aluminum, titanium, steel etc) whereby the wire is melted with an electric arc (WAM) or powder-based (LMD). Two heads deposit the powder, one with a thickness of 2.5 mm, the other of 4 mm. The machine can also perform finishing (machining and polishing) of parts whose surface condition may not be satisfactory, which simplifies the process.

ADDITIVE MANUFACTURING BY INDUCTION

This additive manufacturing prototype machine, which is being jointly developed by an industrial company and Centrale Nantes, uses an alternative source of energy to the electric arc or the laser: induction. It involves passing current through a coil, which creates a magnetic field. The wire then passes through the loop of the inductor. The thread is deposited by adjusting the trajectory. The advantage lies in the cost reduction achieved by removing the need to use a generator, which costs several tens of thousands of euros. Patents have been filed and a thesis is underway on this new technology. The first research papers will be published shortly.

HYBRID ADDITIVE MANUFACTURING

The technology of this machine, for which an international patent was validated in 2011, consists in being able to switch from one manufacturing process to another; in other words, the ability to move, as and when required, from material addition (additive manufacture) to material substraction (machining). This machine also allows powders to be mixed during manufacture to create so-called gradient materials. Some powders have mechanical characteristics, others will respond more to characteristics related to tribology (science of contact). Being able to mix them precisely as they are manufactured prevents a solidification joint forming on the part thus facilitating the interaction and the connection between the two materials, which makes the part more resistant.Projects: joint laboratory with Naval Group, aeronautics, international project with Canadian aviation manufacturer Pratt & Whitney, McGill University in Canada and the University of Sheffield in the United Kingdom, for the manufacture of small parts in titanium powder.

PARALLEL STRUCTURE MACHINE

This prototype machine sets in motion a mass of 150 kg, instead of several tons on other machines, using the five axes of the kinematic chain. It is used for machining, forming and welding. This machine will be useful, for example, for an industrial company who wants to know the forces and power necessary to machine a part, or for another who wishes to test and compare tools, to know their lifetime or if the tool in question cuts well for example. Another question, what strategy to choose to make a part as quickly as possible while respecting the specifications? Depending on the part, the machine offers several possibilities.

WELDING ROBOT "WELDING SPIDER"

The SHIPWELD project, bringing together Centrale Nantes, STX, Tecnalia Spain, the Welding Institute in Portugal and the Universities of Vigo and Cardiff, saw the introduction of an automatic hull welding carriage. As large boats are built in sections, huge and costly scaffolds are needed to weld them. In order to reduce such costs and improve staff safety, the idea emerged of ​​an autonomous welding system that would climb and cross - like a spider - the hull of the ships. No need for scaffolding, the technician can remain at the foot of the boat and follow the carriage’s progress on screen, by camera-feed, and intervene remotely if necessary. The full design, including electronics and computer design, of the carriage was developed at Centrale Nantes. A second project entitled "Charman" was launched via IRT Jules Verne to ensure a transfer of technology (project group STX, Naval Group, Sevisoud, IRT JV).

DIGITAL CONTROL TEST BENCH

This machining center makes it possible to carry out incremental sheet forming, that is to form a part without specific tools.

Incremental sheet forming has none of the drawbacks associated with deep drawing - i.e. frequent corrective action, material resistance, equipment adjustments. Incremental sheet forming consists in taking a sheet on the outside edge and using a metal finger to play on a trajectory to deform the part. The process may take longer than deep drawing, but it provides greater flexibility in that modification of the computer-assisted programming is sufficient to change a part.

This machine is also used to study digitals controls. Several are available on the platform - NUM (French), FIDIA (Italian), Siemens (German) - but they function as black boxes. This is why Centrale Nantes has developed an "open" digital control, known as "Open CN", to determine the algorithmic part and allow a real-time modification of the manufacturing.

The industrial customers of the platform therefore have the choice between these different digital controls for their projects and / or tests. In order to best meet the needs of manufacturers, Centrale Nantes has also developed a software platform for data transfer: the STEP - NC protocol. Used on all machines on the platform, it uses the same programming language for CAD, trajectory and machines. It thus avoids having to reprogram the data in the event of a machine change and to recalculate the desired trajectories.

BIOPRINTING, FROM SCIENCE FICTION TO REALITY

Additive manufacturing first appeared at Centrale Nantes around twenty years ago. Today it is also turning towards medicine with the advent of bioprinting - a technology which uses 3D printing technologies to print living tissue.

The Centrale Nantes team, under the responsibility of Jean-Yves Hascoët, is working closely with Professor Gilles Blancho, Head of Itun* the Institute of Transplantation-Urology and Nephrology of the University Hospital of Nantes, IHU CESTI and the RMES team.

Their collaboration led to the conclusion that it was necessary to acquire a bioprinter to dispense cells. Several such machines exist around the world, but none were available on the market. Nothing is impossible for determined minds - Centrale Nantes and the Nantes University Hospital teams decided to build the machine themselves. This much anticipated machine was assembled and installed on the Centrale Nantes campus in 2016.

This precision machine is now installed in sterile laboratory conditions. It is a three-axis machine with syringes. Engineering and biology meet to determine which needle diameter to use, what pressure to apply, or what degree of viscosity to achieve. After testing, the team master the material and the process. The aim is to investigate the field of grafting and organ transplantation. To avoid patient rejection, the idea is to be able to (re) construct an organ or organ elements from the patient's own stem cells. Next project of the team: vascularize the created matter.

MEASUREMENT CONTROL AREA

Scanner with precision laser (to the nearest micron): scans an existing part to recover the "skin" of the part, controls the parts made in additive manufacturing.Scanning electron microscope: 60,000 magnification, allows an understanding of powder behavior, the structure of the manufactured parts.3D Miscroscope: allows recovery of the surface topology